Current Conditions
Temp0.3 C
RH97 %
WindSSW 26 mph
RoadClosed
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Hawaiian Islands Synoptic Discussion and Guidance

453
FXHW60 PHFO 070631
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
831 PM HST Tue Dec 6 2016

.SYNOPSIS...
A weak surface ridge will remain near the islands and keep winds
gentle for the next week. The winds will be light enough to allow
afternoon sea breezes to develop and produce clouds and showers over
interior areas. Land breezes will produce partial clearing at night.
A trough aloft will linger west of Kauai through the weekend.
Showers will become more active across the state, along with
another bout of wintry weather on the Big Island Summits as the
trough deepens starting Wednesday evening.

&&

.DISCUSSION...
The ZFPHFO product was recently re-issued to include mention of
possible ice accumulation Wednesday night through Thursday night
on the Big Island summit. The associated warning message was also
updated to include more details on the upcoming event.

The general forecast philosophy remains the same as this
afternoon, with no other changes to the forecast grids expected
this evening.

The weak surface ridge near the islands will keep the background
surface winds light through the next week. Winds will be light
enough to allow for afternoon sea breezes, which will result in
clouds and showers forming over the interior of the islands. Land
breezes at night will help to clear at least some of the clouds
out.

An north northeast to south southwest oriented upper level trough
currently about 1100 miles west of Honolulu is forecast to
continue to move to the east over the coming days. The surface
reflection of this system is a touch closer. Layered clouds are
already reaching the islands from the southeast in the upper level
wind flow on the east side of the trough. The models show the
trough digging over the next 24 hours or so, which will bring a more
unstable airmass over the islands that will help to enhance
showers over and near the islands.

This unstable airmass will bring colder temperatures to the
summits of the Big Island. When combined with the moisture that is
expected to reach the nearly 14000 ft summits, there is the
possibility of a mix of wintry weather with snow and ice
possible. The summits are already experiencing reduced visibility
in fog and drizzle. This next bout of winter weather is not
expected to bring as much snow to the summits as the event last
weekend.

With the upper level trough axis expected to slowly move over the
islands through the weekend, expect showers to continue.

&&

.AVIATION...
VFR conditions will prevail across the state overnight and
Wednesday morning, with no AIRMETs expected during that period.

As the trough aloft digs toward the area, clouds and showers will
increase over the islands starting Wednesday afternoon, continuing
into Wednesday night. Areas of MVFR conditions will become likely,
and AIRMET SIERRA for mountain obscuration will probably become
necessary at that time. AIRMET SIERRA for turbulence aloft and
AIRMET ZULU for icing may also be needed.

&&

.MARINE...
Winds and seas are expected to remain below the advisory thresholds
for the next several days. A series of northwest swells will
continue, but surf will remain well below the High Surf Advisory
threshold.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 6 PM Wednesday to 6 AM HST Friday
for Big Island Summits.


&&

$$

DISCUSSION/MARINE...M Ballard
AVIATION...Jacobson

Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office